1,721,077 research outputs found
Structural and magnetic properties of FeχMn1-χ thin films on Cu(001) and on Co/Cu(001)
No full textThe structural and magnetic properties of FexMn1-x alloy thin films deposited on Cu(001) and on Co/Cu(001) are investigated. A layer-by-layer growth mode of the alloy films in a large range of concentration is deduced from the presence of regular oscillations in medium-energy electron-diffraction intensity. Low-energy electron-diffraction experiments reveal that Fe50Mn50 films keep the fcc structure when growing on Cu(001) and on Co/Cu(001). Magneto-optic Kerr effect is used to study the magnetic properties of Co/FeMn bilayers. A temperature-dependent increase in the coercive field of the Co film, when the thickness of the adjacent FeMn film exceeds a certain value, is related to the antiferromagnetic state of the FexMn1-x alloy
Local exchange bias observed by photoemission microscopy
No full textBy using a photoemission electron microscope in combination with X-ray magnetic circular dichroism, the domain configuration in a single crystalline Co film exchange coupled to an Fe50Mn50 film is obtained. The effect of the ferromagnetic/antiferromagnetic interaction is observed to be different in Co domains with different magnetization direction, establishing the fact that the exchange bias' is locally set by the magnetization of the ferromagnetic layer, without external field
Magnetic dichroisms in absorption and photoemission for magnetic characterization in x-ray photoelectron emission microscopy
No full textMagnetic contrast for the operation of a photoelectron emission microscope (PEEM) with synchrotron radiation is provided by magnetic dichroisms. Besides the most frequently employed magnetic dichroism, magnetic circular dichroism in x-ray absorption spectroscopy, energy filtering of photoemitted electrons allows one to also use magnetic dichroisms in photoelectron emission as complementary contrast mechanisms. We demonstrate that it is possible to obtain magnetic contrast in photoemission using PEEM equipped with a simple retarding field electron energy analyzer. Magnetic domain images of an ultrathin film of 10 atomic monolayers of Fe on W(001), obtained by three, different contrast mechanisms (circular magnetic dichroism in x-ray absorption, circular magnetic dichroism in Fe valence band photoemission, and linear magnetic dichroism in Fe 3p photoemission) are presented and compared
Influence of exchange bias coupling on the single-crystalline FeMn ultrathin film
No full textPolarization dependent x-ray photoemission electron microscopy was used to investigate the influence of the exchange bias coupling on the disordered ultrathin single-crystalline fcc Fe(50)Mn(50). We find that the critical thickness of the FeMn film, where the antiferromagnetic (AF) order is formed, varies with changing the magnetization direction of the ferromagnetic (FM) layer from out-of-plane to in-plane. Surface magneto-optical Kerr effect measurements (SMOKE) further manifest the shift of the critical thickness with alternating the exchange bias coupling. It indicates that the spin structure of the FeMn layer near the FM layer is modified by the presence of exchange bias coupling and the properties of the coupling. Our results provide direct experimental evidence that the AF spin structure at the interface between the FM and AF layers is strongly influenced by the exchange bias coupling
Microspectroscopic two-dimensional Fermi surface mapping using a photoelectron emission microscope
No full textWe demonstrate the use of a photoelectron emission microscope in connection with a retarding field electron energy analyzer for the fast acquisition of two-dimensional momentum resolved photoelectron angular distribution patterns. This opens the possibility to combine spatial, momentum, and energy resolution of photoelectrons within the same instrument. We have applied this to observe the Cu(001) Fermi surface from a selected region of the sample. A well defined bulk Fermi surface is quickly mapped in this way
Tuning the magnetic coupling across ultrathin antiferromagnetic films by controlling atomic-scale roughness
No full textCharacterization and control of the interface structure and morphology at the atomic level is an important issue in understanding the magnetic interaction between an antiferromagnetic material and an adjacent ferromagnet in detail, because the atomic spins in an antiferromagnet change direction on the length scale of nearest atomic distances. Despite its technological importance for the development of advanced magnetic data-storage devices and extensive studies, the details of the magnetic interface coupling between antiferromagnets and ferromagnets have remained concealed. Here we present the results of magneto-optical Kerr-effect measurements and layer-resolved spectro-microscopic magnetic domain imaging of single-crystalline ferromagnet - antiferromagnet ferromagnet trilayers. Atomic-level control of the interface morphology is achieved by systematically varying the thicknesses of the bottom ferromagnetic and the antiferromagnetic layer. We find that the magnetic coupling across the interface is mediated by step edges of single-atom height, whereas atomically. at areas do not contribute
Magnetic structure of thin films of FexMn1-x on Cu(100)/Co by the fully relativistic screened KKR method
No full textThe fully relativistic screened Korringa-Kohn-Rostoker method is used to discuss the electronic structure and magnetic properties of FexMn1-x overlayers on Cu(100)/Co. It is found that in this system, energetically low-lying antiferromagnetic configurations most likely are the cause for the experimentally observed antiferromagnetism. In all cases investigated, the ground state corresponds to the (in-plane) ferromagnetic configuration; the FexMn1-x overlayers do carry a small (concentration averaged) magnetic moment. In very good agreement with experiment, two overlayer thicknesses, namely, at 3 and 10 ML, are traced, at which either this moment nearly vanishes (3 ML) or different types of antiferromagnetic configurations apply (10 ML)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Element-selective mapping of magnetic moments in ultrathin magnetic films using a photoemission microscope RID E-5042-2010
No full textWe combine X-ray magnetic circular dichroism (XMCD) and photoelectron emission microscopy to obtain locally resolved magnetic information on a microscopic scale. Scanning the photon energy across elemental absorption edges and recording microscopic images of the local secondary electron intensity for both photon helicities at each photon energy step allows to analyze local XMCD spectra at any position of the imaged area of the sample. With the help of magnetic sum-rules local quantitative information about magnetic moments can be extracted from such microspectroscopic measurements. The full power of XMCD as a spectroscopic tool is so maintained, while microscopic spatial resolution is added
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